So I have a vassal game coming up, a 2v2, I'm paired with BewareOfTom and his Grey Knights, we're facing 2 marines, and I needed to come up with a list, just a quick note on the first Fireknife Squad I'm debating whether to bring a Multi-Tracker or Targeting Array.

On the fire fireknife squad, MT over TA. Bs4 fireknives are known as sha'el and expensive bodyguards.
I have no problems with your firewarriors or other bsuits squads.

But the kroot squad, no need for a shaper, no need for it to be a big blob. Separate it. I don't know how many hounds you got in there.
Why separate it? They are fodder that actually hurt if he doesn't bother with them. Anything he dedicated to shooting or assaulting them should wipe enough out to make them worthless when it is a big blob. Houds adds more teeths to the assault part.

Now, the pathfinders with rail rifles... I don't see the point personally, but perhaps you do. Points could go to upgrade the bodyguard to a shas'el like the first commander or perhaps a few shield drones and team leaders here and there.

The broadside squad... it screams team leader and hard wired target lock. Split those 3 str 10 ap1 shots over a rhino and a pesky land raider.